Simulation and analysis of Ag/ZnO/AZO/Al photodetector

Abstract

The introduction of an aluminum-doped zinc oxide (AZO) buffer layer on a glass substrate has been shown to enhance the performance of Ag/ZnO Schottky photodetectors. To further investigate the correlation between the parameters of AZO buffer layer and ZnO active layer and the performance of Ag/ZnO/AZO/Al photodetectors, we constructed an Ag/ZnO/AZO/Al photodetector based on Silvaco TCAD simulation platform to investigate the effects of AZO layer thickness, ZnO layer thickness, AZO doping concentration, and ZnO doping concentration on the device performance. The simulation results demonstrate that the device achieves better performance when the AZO layer thickness ranges from 0.8 μm to 1.2 μm and the ZnO layer thickness ranges from 0.5 μm to 0.8 μm, with an AZO doping concentration of 1×10¹⁹ cm⁻³ and a ZnO doping concentration of 1×10¹⁶ cm⁻³. Increasing the doping concentration of the AZO buffer layer can enhance the electric field intensity at ZnO-AZO interface, effectively preventing photogenerated holes from approaching ZnO-AZO interface so as to reduce interface recombination; while appropriate ZnO layer thickness and doping concentration can optimize the space charge region width and carrier collection efficiency. Under these optimized conditions, the photodetector reaches its optimum performance with a dark current of 1.1×10⁻⁸ A, a photocurrent of 8.41×10⁻⁶ A, and a responsivity of 0.21 A·W^-1. This research helps reduce the number of experiments and associated costs while preparing low-cost and high-performance ZnO photodetectors.

Keywords

aluminum-doped zinc oxide (AZO) / zinc oxide (ZnO) / Schottky / ultraviolet (UV) photodetector / electric field distribution / dark current

Acknowledgement

This work was supported by Natural Science Foundation of Gansu Province (No. 23JRRA844).

Declaration of conflicting interests

The authors have no conflict of interests related to this publication.

References

[1] NASIRI N,BO R H,WANG F,et al. Ultraporous electron-depleted ZnO nanoparticle networks for highly sensitive portable visible-blind UV photodetectors. Advanced Materials, 2015, 27(29): 4336-4343.

[2] ALAIE Z,MOHAMMAD NEJAD S,YOUSEFI M H. Recent advances in ultraviolet photodetectors. Materials Science in Semiconductor Processing, 2015, 29: 16-55.

[3] OUYANG B S,ZHANG K W,YANG Y. Self-powered UV photodetector array based on P3HT/ZnO nanowire array heterojunction. Advanced Materials Technologies, 2017, 2(12): 1700208.

[4] SHARMA S,PERIASAMY C. Simulation study and performance analysis of n-ZnO/p-Si heterojunction photodetector. Journal of Electron Devices, 2014, 19: 1633-1636.

[5] VARMA T,PERIASAMY C,BOOLCHANDANI D. Performance analyses of Schottky diodes with Au/Pd contacts on n-ZnO thin films as UV detectors. Superlattices and Microstructures, 2017, 112: 151-163.

[6] DAS M, SARMAH S,BARMAN D,et al. Distinct band UV–visible photo sensing property of ZnO-Porous silicon (PS): p-Si hybrid MSM heterostructure. Materials Science in Semiconductor Processing, 2020, 118: 105188.

[7] ISMAIL R A,AL-SAMARAI A E,MOHAMMED W M. Preparation of n-ZnO/p-Si heterojunction photodetector via rapid thermal oxidation technique: effect of oxidation time. Applied Physics A, 2018, 124(8): 527.

[8] LIU Z,CHENG B W. Research progresses of Si-based Ge PIN photodetectors. Semiconductor Optoelectronics, 2022, 43(2): 261-266.

[9] LI H D,JIANG D Y,ZHAO M. High ultraviolet gain in Ga₂O₃/ZnO heterojunction photodetector based on MSM structure. Journal of Alloys and Compounds, 2024, 1005: 176217.

[10] JANARDHANAM V,JYOTHI I,ZUMUUKHOROL M,et al. High gain GaN ultraviolet Schottky photodetector with Al-doped ZnO interlayer. Surfaces and Interfaces, 2021, 27: 101405.

[11] SINGH S. Simulation, fabrication, and characterization of Al-doped ZnO-based ultraviolet photodetectors. Journal of Electronic Materials, 2016, 45(1): 535-540.

[12] AL-KHALLI N,ABOUD M,DEBBAR N. Theoretical study and design of n-ZnO/p-Si heterojunction MSM photodiode for optimized performance. Optics & Laser Technology, 2021, 133: 106564.

[13] AYDOĞAN Ş,GRILLI M L,YILMAZ M,et al. A facile growth of spray based ZnO films and device performance investigation for Schottky diodes: Determination of interface state density distribution. Journal of Alloys and Compounds, 2017, 708: 55-66.

[14] ZHANG C Z,HU T,WANG Z X,et al. Influence of AZO buffer layer on characteristics of ZnO film on glass substrates for Schottky UV photodetector applications. Optical Materials, 2024, 156: 115889.

[15] BANSAL S. Simulation and optimization of Pt/ZnO Schottky UV photodetector with Al ohmic contact//2024 3rd International Conference for Innovation in Technology, March 1-3, 2024, Bangalore, India. New York: IEEE, 2024: 1-6.

[16] YOUSEFIZAD M,GOLSHAN BAFGHI Z,SHAHRIYARI A,et al. Advancements in photovoltaic efficiency: The role of fluorine-doped CZTS in homojunction solar cells. Heliyon, 2025, 11(3): e42300.

[17] MA Y H,ZHANG W Q,CHEN C P,et al. First-principles study on electronic structure and photoelectric properties of Li-doped α-Bi₂O₃. Journal of North University of China (Natural Science Edition), 2023, 44(5): 503-509.

[18] BANSAL S,RAJPOOT A K,CHAMUNDESWARI G,et al. Pt/ZnO and Pt/few-layer graphene/ZnO Schottky devices with Al ohmic contacts using Atlas simulation and machine learning. Journal of Science: Advanced Materials and Devices, 2024, 9(4): 100798.

[19] NOVÁK P,OČENÁŠEK J,KOZÁK T,et al. Identification of electrical properties in individual thickness layers in aluminium-doped zinc oxide films sputtered at 100 ℃. Thin Solid Films, 2018, 660: 471-476.

[20] ZHANG C Z,CHEN Y G,ZHOU Q H. Method for improving properties of ZnO thin films prepared on the glass substrate. Semiconductor Technology, 2019, 44(6): 454-458.

[21] LI Y N,NIE S X,HUANG L L,et al. Paper based self-powered UV photodiode: Enhancing photo-response with AZO back-field layer. Ceramics International, 2023, 49(3): 4831-4838.

[22] YE Z Z,WANG F Z,CHEN F,et al. Wide band gap semiconductor optoelectronic materials and their applications. Acta Optica Sinica, 2022, 42(17): 1716001.